In the Star Trek Fictional universe, Starfleet is the Defense, research, Diplomacy, and Exploration force of the United Federation of Planets. Starfleet Headquarters is located in San Francisco, California, Earth, Sol System, Sector 001, in the Alpha Quadrant.
Starfleet predates the founding of the Federation by several decades, and was responsible for launching the first Human Warp 5-capable starship, the Enterprise NX-01. It is assumed that the pre-Federation Starfleet later expanded to be the UFP version with a technological collaboration on the part of its members.
Many of the Headquarters' buildings are concentrated just east of the Golden Gate Bridge in what is now the Presidio of San Francisco, a park on the northern tip of the San Francisco Peninsula.
Starfleet consists of many branches which make up the organization, namely:
Though Starfleet is comprised of many races, Humans and Vulcan, two of the four founders of the Federation (the other two being the Andorians and the Tellarites), have the most prominent roles in early episodes. As the stories progress into later series, other races such as Bolians, Betazoids, Trills, and others begin to be given central roles.
Starfleet has been shown to handle diplomatic, scientific, and military missions, although their main mandate seems to be one of peaceful exploration. The flagship of Starfleet (and also of the "1st fleet", see Dominion War) is often the starship USS Enterprise.
Most members of Starfleet who handle day-to-day operations are enlisted persons. There are also Warrant Officers and Commissioned Officers in leadership positions. Officers typically serve as department heads and as commanders. Most officers are trained at Starfleet Academy San Francisco, California, Earth in a four-year course which trains them in skills such as warp travel and military tactics. Starfleet ranks and insignia are similar to those used by the United States Navy.